Florida red tide is one of the most notorious of all Harmful Algal Blooms (HABs), occurring on a virtually annual basis along Florida's Gulf coast. The incriminated dinoflagellete, Gymnodinium breve, blooms along the Texas coast, Alabama, parts of Louisiana, and New Zealand. Florida red tide causes major epizootics, produces toxic shellfish when the dinoflagellate is filter-accumulated in clams and oysters, and releases in irritating toxicant into the air when surf conditions are turbulent. There is evidence that brevetoxins are neurotoxins, that they inhibit cell-mediated immunological processes, and they are potent bronchoconstrictors. Very little is known about the toxicological sequelae that accompany human respiratory exposure to toxins in seaspray and wind-dried toxic particles of G. breve. The specific elements are: Facilities Core 1 "Toxins Probes and Assays", provides over 4000L of continuous culture G. breve for producing 40 mg/week standardized natural toxins. Synthetic brevetoxin metabolites and sunlight-modified toxin derivatives will also be produced. Radioimmuno-, enzyme-linked immuno- and immuno- fluorescent assays will be provided to augment synaptosome binding and HPLC analysis for soluble and tissue-fixed quantification and localization of toxin. Facilities Core 2 "Immunohistochemistry" will provide a qualitatively measure of toxin accumulated in cells, tissu8es, and other biological materials derived from the 4 research projects. Development of a quantitative "biomarker of exposure" will be initiated. Research Project 1 "Characterization of Red Tide Aerosols" will seek to determine, in the lab and field, the physical and chemical character, and concentration of toxins in wind and seaspray. Research Project 2 "Inhaled Brevetoxins: Health Effects and Toxicokinetics" will investigate the uptake, distribution, metabolism, and clearance of labeled brevetoxin in animal models. Both single dose and repeat administration will be used. Research Project 3, "Mechanism of Brevetoxin-Induced Bronchial and Nasal Responses in Allergic and Non-Allergic Airways" will be a sheep model investigation of airway contractility in response to brevetoxin challenge. Dose response, drug intervention, mast cell involvement, and synergy with existing asthma or hyperactive airway syndromes will be studied. Research Project 4 "Respiratory Effect Study of Aerosolized Red Tide Toxins on Human..." will collect human throat and nasal swabs to measure brevetoxin. Biomarker data will be collected in conjunction with epidemiologic and clinical data, to better define the acute and chronic effects of exposure. The research overall will contribute to the model of animal and human health effects of aerosolized red tide toxins.